Vacuum powered tools are supplied with negative pressure from a vacuum source, which may be an ejector arranged adjacent to the tool or a centrally arranged ejector or pump that serves several gripping appliances. An appliance, such as a suction cup, can be connected to the vacuum source in order to, by suction effect, generate an engagement with objects that are to be handled by the vacuum powered tool.
In vacuum powered tools that are employed for the handling of objects having uneven or leaning surfaces, the suction cup can be formed as a bellows. The flexibility and compression capacity of the bellows allow an adaptation to the shape or position of the object so that the requisite sealing can be obtained between the object and the bellows, or between the object and an appliance coupled to the bellows such as a suction cup. The flexibility of the bellows is also advantageous in the handling of sensitive or deformable surfaces and materials, and therefore the bellows is an often utilized component in vacuum powered tools.
Bellows for this purpose can be manufactured of rubber or of synthetic rubber mixings and have most often a circular cross-section, but could have a polygonal cross-section. Typically, the bellows have a uniform diameter size that is made up by the external periphery of a number of plate-shaped rings piled on each other, which form a tooth-shaped or sinusoidal profile in a longitudinal cross-section. The bellows are torsion resistant as a result of their structure, but are otherwise universally flexible. However, upon the introduction of negative pressure in the bellows, the bellows typically undergoes an essentially rectilinear axial compression, so as to, when the negative pressure ceases, return to its original shape by an inherent spring force that aims to bring back the bellows to its original length.
Vacuum powered tools that are arranged with bellows are often employed for the sorting or picking of articles and packages. Various types of articles and packages are, however, not equally suitable to be gripped by means of negative pressure and by a suction effect. Accordingly, change from a hard package to a soft one may entail that the bellows and/or an appliance connected to the bellows has to be replaced by an appliance that exercises another form of engagement, such as pinching, clamping, locking, etc.